Gestational Trophoblastic Disease

Developmental anomaly of the placenta that converts the chorionic villi into a mass of clear fluid-filled vesicles.

Two types of moles:

a.Complete moles – neither an embryo nor an amniotic sac. It is characterized by swelling and cystic formation of all trophoblastic cells. No fetal blood is present. If an embryo did develop, it was most likely only 1 to 2 mm in size and died early on. A complete mole is highly associated with the development of choriocarcinoma.

b.Partial mole – embryo (usually with multiple anomalies) and amniotic sac. It is characterized by edema of a layer of the trophoblastic villi with some of the villi forming normally. Fetal blood may be present in the villi, and an embryo up to the size of 9 weeks gestation may be present. Typically, a partial mole has 69 chromosomes in which there are three chromosomes for every one pair.

Major cause of second trimester bleeding.

Also called molar pregnancy or hydatidiform mole.

Pathophysiology

Trophoblastic villi cells located in the outer ring of the blastocyst (the structure that develops via cell division around 3 to 4 days after fertilization) rapidly increase in size, begin to deteriorate, and fill with fluid.

The cells become edematous, appearing a grapelike clusters of vesicles.

As a result, the embryo falls to develop past the early stages.

Causes

Exact cause is unknown

May be associated with poor maternal nutritional (specifically, an insufficient intake of protein and folic acid), a defective ovum, chromosomal abnormalities, or hormonal imbalances.

Preceding molar pregnancy in about 50% of patients with choriocarcinoma.

Preceding spontaneous or induced abortion, ectopic pregnancy, or normal pregnancy in the remaining 50% of patients.

Assessment findings

Disproportionate enlargement of the uterus; possible grapelike clusters noted in the vagina on pelvic examination.